Many modern windows now include vinyl-clad aluminum extrusion or vinyl-clad wooden frames and sashes. A recent trend is to provide the lower sash of double-hung windows with a pair of tilt latches mounted along the top rail. These tilt latches fall into two basic categories, top mount tilt latches and internal tilt latches.
Top mount tilt latches come pre-assembled and include a spring mounted latch within a cover or housing. The housing is mounted to the rail of the lower sash with two or four set screws. Since two tilt latches are provided on such windows, on both the left and right sides of the rail of the lower sash, up to four or more screws are required per sash.
Internal tilt latches are typically inserted within the aluminum or vinyl extrusion of the windows in a preconfigured cavity. Of course, considerable care must be used in constructing the window to provide a suitable internal structure for accommodating such a device.
While the most recent specimens for tilt latches have proven effective in securing tilt windows in place, the cost associated with a large number of set screws and the manufacture of internal window cavities has limited the affordability of such devices.